For example, Virtua Fighter 2 and 3 having better balance in game mechanics and graphics on a technical level, or 3S having better specific implementation of things like parries, etc.). in a way that gels together that no other fighter of that gen quite fully captures (altho I also contest that certain games do specific things better. What I mean by that is: the game just mixes together its game mechanics, graphics, soundtrack, sound effects, character designs, stage designs, CG films, move sets etc.
To me, Tekken 3 on PS1 is the best 'full-package' fighter of its generation. My first experience w/ the series was through PS1 first Tekken 2 at a friend's house, then later Tekken 3 on my own PS1 back around '05 or so.